The breaking point is at 2.  So draw a thin vertical line at x=2,
so you can erase it later:



Get a couple of points using values of x which 
are greater than 2 and use f(x) = -x:

 x | f(x)
 3 | -3
 4 | -4



Connect those points just up to the green line:



--------------------------------------------

Get a couple of points using values of x 
which are less than 2 and use f(x) = x-4:

  x | f(x)
 -2 | -6
  1 | -3



Connect those points just up to the green line:



Erase the green lins:



Edwin